Refrigerating compressor and refrigerating device using the same

ABSTRACT

A refrigerating compressor includes a hermetic container accommodating oil, a motor accommodated in the container, a compressing unit provided under the motor and driven by the motor, and a vibration insulating wall. The compressing unit has a crankshaft, a cylinder block, a piston, a connecting rod and a feed oil pipe. The vibration insulating wall is placed inside the container at the bottom and surrounds the feed oil pipe with a given distance in between.

TECHNICAL FIELD

The present invention relates to a refrigerating compressor to be usedin a refrigerator, and it also relates to a refrigerating device usingthe same compressor.

BACKGROUND ART

A conventional refrigerating compressor including a feed oil pipe dippedin oil is disclosed in Unexamined Japanese Patent Publication No.H11-303740, for example. The conventional compressor is describedhereinafter with reference to FIGS. 5 and 6.

FIG. 5 shows a vertical sectional view of the conventional refrigeratingcompressor, and FIG. 6 shows an essential part enlarged from FIG. 5.Hermetic container 1 accommodates oil 2 and motor 3. Compressing unit 4driven by motor 3 is also accommodated in container 1 under motor 3.

Compressing unit 4 has cylinder block 7 including cylinder 5 and bearing6; and crankshaft 10 including eccentric section 8 and main shaft 9which is supported by bearing 6. Eccentric section 8 of crankshaft 10 isconnected to piston 11 via connecting rod 12. Piston 11 is insertedreciprocally in cylinder 5.

Valve plate 14 seals an opening end of cylinder 5, and discharging valve13 is provided to valve plate 14 on the other side of cylinder 5. Valveplate 14 has suction valve 15. A first end of suction muffler 17communicates with suction valve 15, a second end of suction muffler 17opens into container 1 via sound deadening space 16.

Eccentric section 8 has feed oil pipe 18 at its lower end, and a firstend of oil feed pipe 18 is press-fitted to eccentric section 8 and asecond end thereof is dipped in oil 2. Feed oil pipe 18 is formed of asteel pipe, and is bent to form a V-shape including an obtuse angle suchthat the second end dipped in oil 2 is positioned at the rotating centerof main shaft 9.

The operation of the refrigerating compressor having the foregoingstructure is described hereinafter. The spin of crankshaft 10 by motor 3is transmitted to connecting rod 12, so that piston 11 reciprocates.This reciprocation sucks refrigerant into suction muffler 17, andintermittently sucks the refrigerant into cylinder 5 via suction valve15. The refrigerant flows through an outer cooling circuit (not shown)and is temporarily released into hermetic container 1 before it issucked into suction muffler 17. The refrigerant sucked into cylinder 5is compressed by piston 11, and pushes discharge valve 13 open, so thatthe refrigerant is discharged again into the outer cooling circuit. Oil2 stored in container 1 is drawn through oil feed pipe 18 by centrifugalforce of feed oil pipe 18 placed at the lower end of eccentric section 8and is delivered to respective sliding sections of compressing unit 4.

In the foregoing structure, eccentric section 8 of crankshaft 10 isvibrated by large intermittent loads applied from connection rod 12 whencompressing unit 4 compresses the refrigerant, so that eccentric section8 repeats bending deformation. The vibration of eccentric section 8travels to feed oil pipe 18. Then feed oil pipe 18 is vibrated and thusgenerates resonance sound.

In addition, feed oil pipe 18 rotates in oil 2, thereby agitating oil 2.Oil 2 collides with structural elements of the compressor in container1, and the flow of oil 2 is thus disturbed, so that no neat eddy isformed. In this status, the refrigerant dissolved in oil 2 foams. Thisfoam collides with feed oil pipe 18 following the disturbance of oil 2,thereby vibrating feed oil pipe 18 and generating the resonance sound.This phenomenon is conspicuous particularly when the refrigerant, e.g.hydrocarbon, dissolved much amount in oil 2 is used.

The vibration due to the resonance of feed oil pipe 18 travels tohermetic container 1 via oil 2, and radiates to the outside of container1 as noises, so that the refrigerating compressor becomes noisy.

DISCLOSURE OF INVENTION

The refrigerating compressor of the present invention has a hermeticcontainer accommodating oil; a motor accommodated in the hermeticcontainer; a compressing unit disposed under the motor, accommodated inthe container, and driven by the motor; and a vibration insulating wall.The compressing unit includes a crankshaft, a cylinder block, a piston,a connecting rod, and a feed oil pipe. The crankshaft has a main shaftand an eccentric section. The cylinder block has a bearing forsupporting the main shaft rotatably, and a cylinder. The pistonreciprocates in the cylinder. The connecting rod connects the piston tothe eccentric section. The feed oil pipe is fixed to the eccentricsection, and one of its ends is dipped into the oil. The vibrationinsulating wall is disposed inside of the container at the bottom, andsurrounds the feed oil pipe with a given space in between. Thisstructure allows isolating the resonance sound traveling from the pipeto the container, so that a refrigerating compressor with low noises isobtainable.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a vertical sectional view of a refrigerating compressor inaccordance with an embodiment of the present invention.

FIG. 2 shows an essential part of the compressor enlarged from FIG. 1.

FIG. 3 shows a lateral sectional view of the refrigerating compressorshown in FIG. 1.

FIG. 4 shows a refrigerating cycle of a refrigerating device employingthe refrigerating compressor shown in FIG. 1.

FIG. 5 shows a vertical sectional view of a conventional refrigeratingcompressor.

FIG. 6 shows an essential part enlarged from the conventionalcompressor.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

An exemplary embodiment of the present invention is demonstratedhereinafter with reference to the accompanying drawings. This embodimentdoes not limit the invention.

FIGS. 1, 2 and 3 show a vertical sectional view, a sectional viewillustrating an essential part enlarged, and a lateral sectional view ofthe refrigerating compressor in accordance with the embodiment of thepresent invention, respectively. Refrigerating compressor 50 includeshermetic container 101, motor 106, compressing unit 107, and vibrationinsulating wall 125.

Hermetic container 101 stores oil 102 formed of mineral oil at itsbottom, and is filled with refrigerant 103 formed of hydrocarbon such asR600a (isobutane). Hermetic container 101 accommodates motor 106 havingstator 104 and rotor 105, and compressing unit 107 driven by motor 106.Compressing unit 107 is placed under motor 106.

Next, a structure of compressing unit 107 is described hereinafter.Crankshaft 110 includes main shaft 109, rigidly inserted into rotor 105of motor 106, and eccentric section 108. Cylinder block 114 includesbearing 111 for supporting main shaft 109 rotatably, and cylinder 113,into which piston 115 is inserted for forming compressing room 112.Cylinder block 114 supports stator 104. Eccentric section 108 ofcrankshaft 110 is connected to piston 115 by connecting rod 116.

Feed oil pipe 118 (hereinafter referred simply as “pipe 118”) attachesto the lower end of eccentric section 108 such that a first end of pipe118 is press-fitted to the lower end of eccentric section 108 and asecond end is dipped in oil 102 and placed on an extension line of therotation axis of main shaft 109. Pipe 118 is formed of a steel pipe suchas carbon steel pipe for machine construction, and bent at bent section117 to form a V-shape including an obtuse angle. Feed oil hole 119, intowhich pipe 118 is press-fitted, communicates with respective slidingsections of compressing unit 107.

A structure of hermetic container 101 is described hereinafter. Hermeticcontainer 101 includes lower container 120 and upper container 121 bothformed by drawing hot-rolled sheet steel, for example, and lower andupper containers 120 and 121 are welded at junction 122 by electricwelding. Lower container 120 is equipped with discharge pipe 123 andsuction pipe 124 both connected to the refrigerating cycle detailedlater and shown in FIG. 4.

Valve plate 131 seals an opening end of cylinder 113, and dischargevalve 130 is provided to valve plate 131 on the other side of cylinder113. Valve plate 131 is equipped with suction valve 132. A first end ofsuction muffler 134 communicates with suction valve 132, and a secondend of suction muffler 134 opens into hermetic container 101 via sounddeadening space 133.

FIG. 4 shows a refrigerating cycle of a refrigerating device includingrefrigerating compressor 50. Refrigerating compressor 50 is coupled toheat exchanger 60 on heat absorption side (hereinafter simply referredto as “heat exchanger 60”), namely low pressure side of therefrigerating cycle, by suction pipe 124 shown in FIG. 3. Refrigeratingcompressor 50 is also coupled to heat exchanger 70 on heat radiationside (hereinafter referred simply as “heat exchanger 70”), namely highpressure side of the refrigerating cycle, by discharge pipe 123.Compressed refrigerant 103 is discharged from discharge pipe 123, and issent to heat exchanger 70 for radiating heat, then returns to heatexchanger 60 via expansion valve 80 for absorbing heat. Therefrigerating device is thus formed.

Next, vibration insulating wall 125 disposed in lower container 120 isdescribed hereinafter. Vibration insulating wall 125 is shaped like acup and is placed inside lower container 120 at the bottom so that itsurrounds pipe 118 with a given distance in between. Vibrationinsulating wall 125 is made of the material such as metal andpolybutylene terephthalate resin which is not swelled by refrigerant 103or oil 102.

Vibration insulating wall 125 is sandwiched by fixing nut 127 and thebottom of lower container 120 with fixing bolt 126. Fixing bolt 126extends through the bottom of vibration insulating wall 125 and weldedto lower container 120 by electric welding. Fixing nut 127 is screwed onbolt 126.

The operation of the refrigerating compressor having the foregoingstructure is demonstrated hereinafter. Motor 106 in operation promptsrotor 105 to rotate crankshaft 110, thereby reciprocating piston 115 incylinder 113 via connecting rod 116. This motion allows refrigerant 103,flowing from heat exchanger 60 shown in FIG. 4, to pass through suctionpipe 124 and be released temporarily into hermetic container 101, thenbe sucked into suction muffler 134, and be drawn intermittently intocompressing room 112 in cylinder 113 via suction valve 132. Refrigerant103 flowing into compressing room 112 is compressed by piston 115reciprocating in cylinder 113, then pushes discharge valve 130 open, sothat refrigerant 103 is discharged from discharge pipe 123 to heatexchanger 70 shown in FIG. 4.

Pipe 118 rotates together with crankshaft 110. The first end of pipe 118is press-fitted into eccentric section 108 roughly at the center. Thesecond end of pipe 118 is dipped in oil 102 and positioned on theextension line of the rotation axis of main shaft 109, so that thecentrifugal force due to the rotation works on oil 102 in pipe 118. Thiscentrifugal force works as pumping force which delivers, via feed oilhole 119, oil 102 inside vibration insulating wall 125 to respectivesliding sections of compressing unit 107.

Compression load applied to piston 115 allows applying loadsintermittently to eccentric section 108, which thus repeats bendingdeformation. This deformation of eccentric section 108 travels asvibration to pipe 118, thereby vibrating pipe 118, so that pipe 118generates resonance. However, in refrigerating compressor 50, vibrationinsulating wall 125 cuts off the travel of the resonance of pipe 118 tohermetic container 101. As a result, the vibration travelling from pipe118 to lower container 120 is attenuated, and the noise to be radiatedfrom hermetic container 101 to the outside is suppressed to a lowerlevel.

Vibration insulating wall 125 is preferably made of vibration dampingmaterial such as polybutylene terephthalate resin, so that a greateramount of attenuation is obtainable and the noise radiated to theoutside of hermetic container 101 can be suppressed to an excessivelylow level.

It is preferable that communicating hole 128 having a smaller diameterthan an inner diameter of pipe 118 is provided at the lower part ofvibration insulating wall 125. This structure allows continuous supplyof oil 102 from the outside of vibration insulating wall 125 throughcommunicating hole 128 into the inside of vibration insulating wall 125even if the surface of oil 102 inside wall 125 lowers. As a result,supply of oil 102 is never cut off to the respective sliding sections ofcompressing unit 107.

Upper end 129 of vibration insulating wall 125 preferably extends upwardand exceeds the surface of oil 102. This structure allows oil 102 insidevibration insulating wall 125 to communicate with oil 102 in hermeticcontainer 101 only through communicating hole 128. Hole 128 has adiameter smaller than that of pipe 118 so that no oil shortage occursinside vibration insulating wall 125, so that few vibrations travel frompipe 118 to hermetic container 101 via communicating hole 128. As aresult, vibration insulating wall 125 effectively isolates the resonanceof pipe 118.

Next, the situation where bubbles of refrigerant 103 collide with pipe118, is demonstrated hereinafter. When refrigerating compressor 50starts operating, the inside of hermetic container 101 is decompressed.As a result, refrigerant 103 dissolved in oil 102 during the halt ofrefrigerating compressor 50 starts foaming. The bubble of refrigerant103 generated at this time draws an eddy-like path following therotation of pipe 118, and the bubbles are drawn to the tip of pipe 118together with oil 102. At this time, when the bubbles is drawn togetherwith oil 102 disturbed around pipe 118 to the tip of pipe 118, thebubbles collide with the inner and outer walls of pipe 118, so that pipe118 is greatly vibrated.

Considering the status discussed above, it is preferable that the innerwall of vibration insulating wall 125 shapes like a smooth body ofrevolution revolving on an extension line of the rotation axis of mainshaft 109. This shape is free from inward protrusions, so that oil 102inside vibration insulating wall 125 rotates in a conical shape withoutdisturbance following the rotation of pipe 118. As a result, drawing asmooth circle, the bubbles of refrigerant 103 in oil 102 approach to thetip of pipe 118, so that collisions between the bubbles and the insideor outside wall of pipe 118 decrease drastically. Oil 102 including thebubbles is thus smoothly drawn into pipe 118, and the resonance of pipe118 decreases also drastically.

Refrigerant 103 such as hydrocarbon and oil 102 such as mineral oil oralkyl benzene are mutually soluble with each other, so that refrigerant103 dissolved in oil 102 during the halt of refrigerating compressor 50abruptly starts foaming when refrigerating compressor 50 startsoperating. After this abrupt foaming is finished, refrigerant 103 in oil102 more or less foams successively during the operation ofrefrigerating compressor 50.

In this embodiment, refrigerant 103 easy to foam is combined with oil102. A noise level of hermetic container 101 due to resonance can belowered even if the resonance of pipe 118 frequently occurs due to thecollision between the bubbles and pipe 118 with this combination. Thisis because vibration insulating wall 125, formed of the vibrationdamping member, efficiently damps the vibration travelling in oil 102,thereby reducing drastically the vibration transmitted to the outside ofvibration insulating wall 125. As discussed above, even use of pipe 118,weakening the noise of refrigerating compressor 50 to an excessively lowlevel is allowed. Pipe 118 made of a steel pipe such as a carbon steelpipe for machine construction is just bent at bent section 117 to form aV-shape including an obtuse angle, so that pipe 118 is obtainable at ahigh productivity.

Pipe 118 violently agitates oil 102, which thus splashes from the oilsurface, so that the oil drops scatter. This particular case isdescribed hereinafter. When pipe 118 rotates in oil 102 during theoperation of refrigerating compressor 50, the centrifugal force works onoil drops attached to the outer wall of pipe 118. This centrifugal forcesometimes produces oil drops splashed and separated from the oil surfaceof oil 102. The oil drop, in general, splashes along the outer rim ofpipe 118 and collides with hermetic container 101 or compressing unit107, thereby causing noises.

Upper end 129 of vibration insulating wall 125 preferably extends upwardand exceeds bent section 117 of pipe 118. This structure allows theinner face of vibration insulating wall 125 to catch the oil dropssplashed by pipe 118, so that the scatter of oil drops is prevented fromcolliding with hermetic container 101 or compressing unit 107. As aresult, noises can be prevented.

In this embodiment, vibration insulating wall 125 made of resin such aspolybutylene terephthalate resin is used; however, vibration dampingsteel plate or rubber such as nitrile-butadiene rubber can be usedinstead of the resin, and these materials produce an advantage similarto what is discussed above. Cold-rolled sheet steel, which isinexpensive and highly formable, can be used as the material ofvibration insulating wall 125 with an advantage similar to the foregoingone.

INDUSTRIAL APPLICABILITY

A refrigerating compressor of the present invention is useful for arefrigerating device to be used in a home-use refrigerator whichrequires quiet operation, and it is applicable to business-userefrigerators to be used in hotels or a medical care industry.

-   1 hermetic container-   2 oil-   3 motor-   4 compressing unit-   5 cylinder-   6 bearing-   7 cylinder block-   8 eccentric section-   9 main shaft-   10 crankshaft-   11 piston-   12 connecting rod-   13 discharge valve-   14 valve plate-   15 suction valve-   16 sound deadening space-   17 suction muffler-   18 feed oil pipe-   50 refrigerating compressor-   60 heat exchanger on heat absorption side-   70 heat exchanger on heat radiation side-   80 expansion valve-   101 hermetic container-   102 oil-   103 refrigerant-   104 stator-   105 rotor-   106 motor-   107 compressing unit-   108 eccentric section-   109 main shaft-   110 crankshaft-   111 bearing-   112 compressing room-   113 cylinder-   114 cylinder block-   115 piston-   116 connecting rod-   117 bent section-   118 feed oil pipe-   119 feed oil hole-   120 lower container-   121 upper container-   122 junction-   123 discharge pipe-   124 suction pipe-   125 vibration insulating wall-   126 fixing bolt-   127 fixing nut-   128 communicating hole-   129 upper end-   130 discharge valve-   131 valve plate-   132 suction valve-   133 sound deadening space-   134 suction muffler

1. A refrigerating compressor comprising: (a) a hermetic containeraccommodating oil; (b) a motor accommodated in the hermetic container;(c) a compressing unit disposed under the motor, accommodated in thecontainer, and driven by the motor, the compressing unit including:(c-1) a crankshaft having a main shaft and an eccentric section; (c-2) acylinder block having a bearing for supporting the main shaft rotatably,and a cylinder, (c-3) a piston reciprocating in the cylinder; (c-4) aconnecting rod coupling the piston with the eccentric section; (c-5) afeed oil pipe attached to the eccentric section and having an end dippedinto the oil; and (d) a vibration insulating wall disposed inside thecontainer at a bottom and surrounding the feed oil pipe with a givendistance in between.
 2. The refrigerating compressor according to claim1, wherein the vibration insulating wall is provided with acommunicating hole having a diameter smaller than an inner diameter ofthe feed oil pipe.
 3. The refrigerating compressor according to claim 2,wherein an upper end of the vibration insulating wall extends upward andexceeds a surface of the oil.
 4. The refrigerating compressor accordingto claim 1, wherein the vibration insulating wall is formed of vibrationdamping material.
 5. The refrigerating compressor according to claim 1,wherein the feed oil pipe is formed of steel pipe, has a bent section,and is shaped as a V-shape including an obtuse angle.
 6. Therefrigerating compressor according to claim 5, wherein an upper end ofthe vibration insulating wall extends upward and exceeds the bentsection.
 7. The refrigerating compressor according to claim 1, whereinan inner wall of the vibration insulating wall is shaped as a body ofrevolution.
 8. The refrigerating compressor according to claim 1,wherein the oil is one of mineral oil and alkyl benzene, and thecompressor compresses hydrocarbon as refrigerant.
 9. A refrigeratingdevice comprising: the refrigerating compressor as defined in claim 1; aheat exchanger on heat radiation side coupled with the refrigeratingcompressor; an expansion valve coupled with the heat exchanger on heatradiation; and a heat exchanger on heat absorption side coupled with theexpansion valve for running refrigerant having undergone heat-absorptionto the refrigerating compressor.
 10. The refrigerating device accordingto claim 9, wherein the refrigerant is hydrocarbon, and the oil is oneof mineral oil and alkyl benzene.